<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <form id="f1">
      <input type="text" />
      <hr />
      <button>hello</button>
    </form>
    <script>
      console.log(document.forms.f1);
      console.log(document.forms.f1.elements);
    </script>
  </body>
</html>
